The present invention relates to a raising machine including positively controlled raising cylinders.
Prior raising machines usually comprise a plurality of raising cylinders, which are circumferentially arranged on a supporting framework which can turn about a rotary axis therefor.
A prior driving system for rotatively driving the raising cylinders provides to use a trapezoidal belt, which, however, is affected by a lot of drawbacks, for example the trend to slipping as said belt is subjected to forces exceeding a set threshold, thereby limiting the operating performance of the raising machine and, accordingly, the raising effect on the fabric material being processed.
Other driving systems, using a plurality of driving gears, have not been found to perform satisfactorily, because of the complexity and great noise of said devices.
A system overcoming the timing problems of the several raising cylinders and preventing the drive system from slipping comprises a raising machine including, for each working cylinder, a toothed pulley, thereabout are entrained a driving belt as well as a timing belt, in order to hold the toothed pulleys synchronized with the teeth of the driving belt.
However, this system, while solving the above mentioned problems, requires to use a timing or synchronization belt affecting all of the raising cylinders.
Moreover, in this prior system, the toothed pulleys pertaining to the raising cylinders must house, on suitable adjoining engagement regions thereof, both the driving belt and the timing belt, with a consequent very complex construction.